Spywareblaster works with mozilla firefox and IE. It is not needed with Opera.
excerpt below from Javacools Faqs.
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(SpywareBlaster does not offer protection for Opera at this time. Since Opera does not support ActiveX, malware isn't as big an issue with the Opera browser.

Note: Many programs use Internet Explorer as a default browser. So even if you use Opera all of the time, SpywareBlaster will protect you when Internet Explorer is opened as a default browser.)